The present invention relates to an Al or Al alloy poppet valve in an internal combustion engine, and a method of manufacturing the same.
Inlet and exhaust poppet valves in an internal combustion engine for a vehicle is generally made of heat-resistant steel such as martensite and austenite. Recently an inlet valve which has relatively low thermal load is made of Al alloy.
The heat resistant steel valve has high mechanical strength, and provides high durability and reliability, but has high inertia mass and low heat conductivity.
The Al alloy inlet valve which is light decreases inertia mass of a valve-operating mechanism, and increase engine performance, thereby providing high heat conductivity and high heat release performance to the cylinder head to increase cooling performance of the engine.
However, Al alloy has low mechanical strength and especially low wear resistance on the valve face to provide low durability and reliability.